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Ga2O3 has generated considerable interest as a wide bandgap semiconductor and is used for solar-blind deep ultraviolet photodetectors. Additionally, graphene serving as a transparent electrode material can improve device performance. However, due to defects at the contact interface between graphene and Ga2O3, existing devices based on graphene/Ga2O3 are liable to elevated dark currents. In this work, we constructed a graphene/β-Ga2O3/Ag asymmetric Schottky junction photodetector, which addresses this issue. Taking advantage of the asymmetric structure design to suppress dark current and the transparent graphene electrode increasing the carrier collection efficiency, the device achieved an outstanding responsivity of 44.09 A W−1, a high detectivity of 5.84 × 1012 Jones, a remarkable external quantum efficiency of 2.15 × 104%, and a fast response time of 99.60 ms/27.74 ms. More importantly, owing to reverse bias voltage on the high barrier side, it possesses a low dark current of 12.09 pA with a light-to-dark ratio of up to 104. All in all, the graphene/β-Ga2O3/Ag asymmetric Schottky junction photodetector has considerable potential as a deep ultraviolet detector. [ABSTRACT FROM AUTHOR]

A novel p–i–n self-powered solar-blind UV photodetector based on p-type spiro-MeOTAD (spiro), Ga2O3, and n-type Si is fabricated. The p-type spiro film is spin-coated on the surface of the Ga2O3 film deposited on a Si wafer via a metal–organic chemical vapor deposition (MOCVD) system. Benefitting from the superior carrier-separation ability of the double built-in electric fields, the effective carrier transport of the novel vertical structure and the high solar-blind UV transmittance of the spiro film, the self-powered responsivity of the p–i–n-type photodetector based on spiro/Ga2O3/Si increases to 4.43 mA W−1 under UV light (λ = 254 nm), which is ∼54-fold that of the Ga2O3/Si photodetector (0.22 mA W−1). Meanwhile, the response speed (0.03/0.196 s) of the p–i–n device is also dramatically improved by introducing the spiro layer. The reported achievements of our work provide a new way to construct a high-sensitivity self-powered UV photodetector for photovoltaic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

By acting as the trapping centers during charge carrier transfer, oxygen vacancy (VO) plays a critical role in oxide photoelectric devices. Herein, a post-annealing method was introduced to perfect the photodetection performances of ε-Ga2O3 photodetectors (PDs) by improving the film quality and modulating the VO defect concentration. The native oxygen-deficient ε-Ga2O3 epitaxial films fabricated via metal–organic chemical vapor deposition become highly dense and VO-less after oxidation annealing, leading to an enhanced performance, while they become VO-rich after reduction annealing to depress the PD property. Compared with the pristine PD, the crucial parameters of the devices with a lower VO concentration have been improved by 1–6 magnitude with a high photo-to-dark current ratio of 1.06 × 108, a large responsivity of 1.368 A W−1, an excellent detectivity of 9.13 × 1014 Jones, a superior linear dynamic range of 176.7 dB and an outstanding external quantum efficiency of 666.5% and a record-high rejection ratio (R240/R400) of 1.80 × 107. As the VO defect is commonly ubiquitous in oxide materials, our investigation of regulating the VO concentrations in ε-Ga2O3 and then exerting influences on the PD capabilities will provide principles for designing high-performance photoelectric devices. [ABSTRACT FROM AUTHOR]